ES2916829T3 - Substrate equipped with a multilayer comprising a partial metal film, glazing unit and method - Google Patents

Abstract

The invention relates to a substrate (30) coated on one side (31) with a thin-film multilayer (34) comprising at least one functional metal film (140) based on silver or made of silver and two antireflection coatings ( 120, 160, 160), said antireflection coatings comprising at least one antireflection layer (124, 164), said functional film (140) being placed between the two antireflection coatings (120, 160), characterized in that functional metal film (140) is a discontinuous film that provides a degree of surface coverage comprised between 50% and 90% or even between 53% and 83%. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Substrate equipped with a multilayer comprising a partial metal film, glazing unit and method

The invention relates to a transparent substrate specifically made of a rigid mineral material such as glass, said substrate being coated with a multilayer of thin layers comprising one or more functional layers that can act on solar radiation and/or long-infrared radiation. long wave

The invention relates more particularly to a substrate, specifically a transparent glass substrate, which has a multilayer of thin layers comprising an alternation of "n" metallic functional layers, specifically functional layers based on silver or a metallic alloy containing silver. , and “(n 1 )” antireflective coatings, where n is an integer > 1, such that the or each functional layer is disposed between two antireflective coatings. Each anti-reflective coating comprises at least one anti-reflective layer, each coating preferably being composed of a plurality of layers, of which at least one layer, or even each layer, is an anti-reflective layer. The notion of antireflective layer is in this case synonymous with that of dielectric layer; especially using the notion of dielectric layer in opposition to the notion of metallic functional layer, which due to its metallic nature cannot be dielectric.

The invention also relates more particularly to the use of said substrates to manufacture thermal insulation glazing and/or solar protection glazing. These glazing units can be designed to equip both buildings and vehicles, with a specific objective of reducing the air conditioning load and/or to prevent excessive overheating (glazing units called “solar control panels”) and/or reduce the amount of energy dissipated to the outside (glazing units called “low emission panels”), due to the increasing areas of glazed surfaces in buildings and in passenger compartments of vehicles.

These substrates can be integrated in particular into electronic devices and the multilayer can then be used as an electrode for conducting a current (lighting device, display device, photovoltaic panel, electrochromic glass panels, etc.) or can be integrated into glazing units with particular functionality, such as, for example, heating glass panels.

One type of multilayer structure known to provide substrates with such properties is composed of a functional metallic layer with reflective properties in the infrared and/or for solar radiation, namely a metallic functional layer based on silver or a metallic alloy containing silver or fully realized silver.

Therefore, in this type of multilayer, the functional layer is arranged between two dielectric antireflective coatings, each one generally comprising several layers each consisting of a nitride-type antireflective material, and specifically a nitride or silicon oxide. or aluminum.

However, sometimes a blocking coating is inserted between one or each anti-reflective coating and the metallic functional layer; the blocking coating located under the functional layer in the direction of the substrate protects it during an optional high temperature heat treatment, such as bending and/or tempering, and the blocking coating located above the functional layer on the opposite side of the substrate protects it layer against any degradation during deposition of the top anti-reflective coating and during an optional high temperature heat treatment, such as bending and/or tempering.

Currently, it is generally desired that each metallic functional layer be a complete layer, in other words, composed throughout its entire surface area and throughout its entire thickness of the metallic material in question.

Those skilled in the art consider that, for a given material (for example, silver), under the usual deposition conditions for this material, only a complete layer is obtained beyond a certain thickness.

The adhesion energy between a full layer of silver and the anti-reflective layers is very low, on the order of about 1 J/m2, and the adhesion energy between two anti-reflective layers is five to nine times that of silver and one other. layer. Therefore, the adhesion energy of a multilayer comprising at least one silver or silver-based functional layer is limited by this low adhesion energy of a complete metallic functional layer with the other materials.

The prior art knows, from document US 2011/0236715, examples with three functional layers of silver and with the central layer being a discontinuous layer.

The inventors have considered the possibility of depositing multilayers of thin layers with one or more metallic functional layers and, for the single metallic functional layer or all these metallic functional layers when there are several of them, with a thickness less than the minimum thickness required to obtain a full layer under the conditions in question. Therefore, the inventors have observed that, for obvious reasons, the resistance per square of the multilayer was higher than with the same multilayers having one or more complete functional layers, but that, nevertheless, this resistance per square could allow certain applications. . Above all, the inventors have observed that the adhesion energy of the multilayer was then greater than that predicted by the theoretical models.

The inventors then observed that very high mechanical resistances could be obtained, and even, what is more surprising, very high chemical resistances, for multilayers comprising a single metallic functional layer, this metallic functional layer being discontinuous, and also for multilayers comprising several metallic functional layers, all of these metallic functional layers being discontinuous.

In addition, the inventors have observed that the multilayers formed in this way were transparent, without haze or surface corrosion, and with colors, both in transmission and in reflection, that could be similar to those obtained with the multilayers having layer(s) complete metal functional(s).

Finally, the inventors have observed that these excellent mechanical and chemical resistance properties are preserved even if the substrate coated with the multilayer is subjected to a heat treatment for shaping, dip coating or annealing.

Therefore, this observation opens the way to the use of this type of multilayer for applications for which it is acceptable that a metallic functional layer, or each metallic functional layer, shows a relatively high resistance per square (for example, greater than 10 Q /square) and for which the high adhesion energy, which has a favorable effect on the mechanical resistance, or even sometimes on the chemical resistance, is a great advantage.

So, in the context of the example above, it is possible to form a multilayer of thin layers that in fact have a higher strength per square than if some or all of the functional layers of the multilayer are complete, but which is particularly strong and so it can be used in regions where climatic conditions impose severe restrictions.

Therefore, the object of the invention, in its broadest sense, is a substrate according to claim 1. This substrate is coated on one side with a multilayer of thin layers comprising at least one metallic functional layer based on silver or made of silver. silver and two anti-reflective coatings, each of said anti-reflective coatings comprising at least one anti-reflective layer, said functional layer being disposed between the two anti-reflective coatings; said (that is, the only metallic functional layer of the multilayer when the multilayer comprises a single metallic functional layer based on silver or made of silver), or each (that is, all the metallic functional layers of the multilayer when the multilayer comprises several metallic functional layers based on silver or made of silver) metallic functional layer is a discontinuous layer having a surface area occupancy factor in the range of 50% to 98%, or 53% to 83% , or even between 63% and 83%.

According to the invention, the functional layer deposited in this way, or each functional layer deposited in this way, is a self-structured layer having a structure in the form of interconnected islands, with uncovered areas between the islands.

Since the metallic functional layer, when it is the only metallic functional layer of the multilayer, or each metallic functional layer when there are several metallic functional layers in the multilayer, is not continuous, this allows direct contact between the layers surrounding the or each metallic functional layer based on silver or made of silver. These regions have strong adherence. Any possible cracks developed at the weakest contact surface, thus the one between the silver and the adjacent layer, will also need to propagate between the two anti-reflective layers to advance, which requires a higher energy. Therefore, in this way, the global adhesion energy of the multilayer is considerably improved.

It is important that the multilayer of thin layers does not comprise any metallic functional layer based on silver or made of silver that is continuous because the presence of at least one such continuous layer reduces the adhesion energy at the two contact surfaces of this layer. continuous metallic functional layer or of each continuous metallic functional layer and, consequently, decreases the strength properties of the entire multilayer by a “weakest link” phenomenon.

In the sense of the present invention, "discontinuous layer" should be understood to mean that, when a square of any given dimension is considered on the surface of the multilayer according to the invention, then, within this square, the discontinuous functional layer is only present in 50% to 98% of the square area, or 53% to 83% of the square area, or even 63% to 83%, respectively.

The square in question is located within a main part of the coating; in the context of the invention, the idea is not to form a particular edge or a particular contour which will later be hidden from the end use.

The discontinuity is such that it is possible to measure a finite resistance per square by the usual technique. Therefore, it is a question of obtaining a discontinuous functional layer (or each discontinuous functional layer) for which the groupings of metallic material that constitute the layer are separated by volumes of total absence of this material but are connected to each other.

According to the invention, this type of self-structured multilayer with functional layer(s) has an adhesion energy that is higher than multilayers with continuous functional layer(s) and its optical properties (transmission light reflection, emissivity) are reduced while remaining within acceptable ranges for certain specific applications (mainly for regions with hot or temperate climates) for which an emissivity level of approximately 20% to 30% may be adequate .

"Coating" within the meaning of the present invention should be understood to mean that there may be only one layer or several layers of different materials within the coating.

The term "multilayer" should be understood to mean an assembly of thin layers deposited one on top of the other, without interposing a mineral (such as glass) or organic (such as a sheet of plastic material) substrate between these layers.

As usual, “layer based on a material” should be understood to mean that the layer is composed predominantly of this material, i.e. the chemical element of the material, or possibly the product of the material in question in its stable stoichiometric formula, constitutes at least 50%, in atomic percentage of the layer in question.

As is also usual, it should be understood that "anti-reflection layer" in the sense of the present invention means that, from the point of view of its nature, the material is "non-metallic", that is, it is not a metal. In the context of the invention, this term denotes a material that has a n/k ratio over the entire wavelength range of the visible region (from 380 nm to 780 nm) that is equal to or greater than 5.

It is recalled that n denotes the real refractive index of the material at a given wavelength and k represents the imaginary part of the refractive index at a given wavelength; calculating the ratio n/k at a given wavelength.

The refractive index values reported herein are the values routinely measured at the wavelength of 550nm.

According to the invention, said or each discontinuous metallic functional layer has a thickness e:

- 1.0 < and < 4.5 nm, or even 1.0 < and < 4.0 nm; or 2.0 < and < 4.5 nm, or even 2.0 < and < 4.0 nm, deposited on a layer based on titanium dioxide TiO2, or

- 1.0 < and < 4.5 nm, or even 1.0 < and < 4.0 nm; or 2.0 < and < 4.5 nm, or even 2.0 < and < 4.0 nm, deposited on a layer based on zinc tin oxide SnZnOx, or

- 1.0 < and < 5.0 nm, or even 1.0 < and < 4.5 nm; or 2.0 < and < 5.0 nm, or even 2.0 < and < 4.5 nm, deposited on a layer based on zinc oxide ZnO, or

- 1.0 < and < 7.0 nm, or even 1.0 < and < 6.0 nm; or 2.0 < and < 7.0 nm, or even 2.0 < and < 6.0 nm, deposited on a layer based on silicon nitride Si3N4, or

- 1.0 < and < 5.0 nm, or even 1.0 < and < 4.0 nm; or 2.0 < and < 5.0 nm, or even 2.0 < and < 4.0 nm, deposited on a nickel-based layer.

Preferably, the multilayer according to the invention is deposited directly on the face of the substrate.

For a multilayer according to the invention comprising a single discontinuous metallic functional layer:

- In a particular version of the invention, said antireflective coating arranged between the face and said metallic functional layer comprises a medium index antireflective layer made of a material having a refractive index in the range between 1.8 and 2.2 , this medium index antireflection layer being preferably oxide based. This medium index antireflection layer can have a physical thickness in the range of 5 to 35 nm.

- It is further possible that said anti-reflective coating arranged under said metallic functional layer comprises a high-index anti-reflective layer made of a material having a refractive index in the range between 2.3 and 2.7, this high index anti-reflective layer preferably being oxide-based and/or this high index anti-reflective layer preferably having a physical thickness in the range between 5 and 25 nm.

- In another particular version of the invention, said antireflective coating arranged on top of said metallic functional layer on the opposite side with respect to the face comprises a medium index antireflective layer made of a material having a refractive index in the range between 1 .8 and 2.2, said medium index antireflection layer being preferably oxide based. This medium index antireflection layer preferably has a physical thickness in the range of 5 to 35 nm.

It is further possible that said antireflective coating arranged on top of said metallic functional layer comprises a high index antireflective layer made of a material having a refractive index in the range between 2.3 and 2.7, this index antireflective layer being high index preferably oxide based and/or this high index antireflective layer preferably having a physical thickness in the range between 5 and 25 nm. Said multilayer may comprise only two discontinuous metallic functional layers based on silver or made of silver and three anti-reflective coatings, each metallic functional layer being disposed between two anti-reflective coatings.

Said multilayer may comprise only three discontinuous metallic functional layers based on silver or made of silver and four anti-reflective coatings, each discontinuous metallic functional layer being disposed between two anti-reflective coatings.

For a multilayer according to the invention comprising several discontinuous metallic functional layers:

- In a particular version of the invention, said antireflective coating disposed between the face and the first, or below each, metallic functional layer comprises a medium index antireflective layer made of a material having a refractive index in the range between 1.8 and 2.2, this medium index antireflection layer being preferably oxide based. This medium index antireflection layer can have a physical thickness in the range of 5 to 35 nm.

- It is further possible that said anti-reflective coating arranged under the first, or under each, metallic functional layer comprises a high-index anti-reflective layer made of a material having a refractive index in the range between 2.3 and 2.7, this high index antireflective layer being preferably oxide based and/or this high index antireflective layer preferably having a physical thickness in the range of between 5 and 25 nm.

- In another particular version of the invention, said antireflective coating arranged above the last, or above each, metallic functional layer on the opposite side with respect to the face comprises a medium index antireflective layer made of a material having an index of refraction in the range between 1.8 and 2.2, said medium index antireflection layer being preferably oxide based. This medium index antireflection layer preferably has a physical thickness in the range of 5 to 35 nm.

- It is further possible that said anti-reflective coating arranged on top of the last, or on top of each, metallic functional layer comprises a high-index anti-reflective layer made of a material having a refractive index in the range between 2.3 and 2, 7, this high index anti-reflective layer preferably being oxide-based and/or this high index anti-reflective layer preferably having a physical thickness in the range of between 5 and 25 nm.

In another particular version of the invention, at least one functional layer is deposited directly on a lower barrier coating disposed between the functional layer and the antireflective coating underlying the functional layer and/or at least one functional layer is deposited directly under a coating Barrier top layer disposed between the functional layer and the anti-reflective coating on the functional layer and the barrier bottom layer and/or the barrier top layer comprises a thin nickel-based or titanium-based layer having a physical thickness e' such that that 0.2nm < e' < 2.5nm.

The last layer of the overlay anti-reflection coating, the one farthest from the substrate, can be oxide-based, and is then preferably deposited sub-stoichiometrically; specifically, it can be based on titanium dioxide (TiOx) or based on a mixed oxide of zinc and tin (SnzZnyOx).

Thus, the stack may comprise a final layer (or topcoat), which is a protective layer, preferably deposited substoichiometrically. This layer oxidizes, for the most part, stoichiometrically within the stack after deposition.

The invention further relates to multiple glazing comprising at least two substrates held together by a frame structure, said glazing forming a separation between an external space and an internal space, in which at least one gas separation layer it is disposed between the two substrates, being a substrate according to the invention.

In a particular variant, the multilayer according to the invention is positioned on face 4 of the glazing unit.

The glazing according to the invention incorporates at least the substrate carrying the battery according to the invention, potentially associated with at least one other substrate. Each substrate can be transparent or colored. One of the substrates can, at least especially, be made of mass-tinted glass. The choice of the type of coloring will depend on the level of light transmission desired and/or the colorimetric appearance desired for the glazing unit once manufactured.

The glazing unit according to the invention may have a laminated structure, specifically associating at least two rigid glass-type substrates by means of at least one sheet of thermoplastic polymer, to obtain a glass-type structure/multilayer of thin layers/sheet(s). )/glass/glass type sheet. The polymer may especially be based on polyvinyl butyral PVB, ethylene vinyl acetate EVA, polyethylene terephthalate PET or polyvinyl chloride PVC.

The invention further relates to the use of at least one metallic functional layer based on silver or made of silver and two anti-reflective coatings to form a thin-layer multilayer coated substrate, and in particular a substrate according to the invention, said (i.e., the single metallic functional layer of the multilayer when the multilayer comprises a single metallic functional layer based on silver or made of silver), or each (i.e. all the metallic functional layers of the multilayer when the multilayer comprises several metallic functional layers based on silver or made of silver) metallic functional layer a discontinuous layer having a surface area occupancy factor in the range of 50% to 98%, or 53% to 83%, or even 63 % and 83%.

The invention further relates to the use of at least one metallic functional layer based on silver or made of silver and two anti-reflective coatings to form a thin-layer multilayer coated substrate, and in particular a substrate according to the invention, said (i.e., the single metallic functional layer of the multilayer when the multilayer comprises a single metallic functional layer based on silver or made of silver), or each (i.e. all the metallic functional layers of the multilayer when the multilayer comprises several metallic functional layers based on silver or made of silver) metallic functional layer a discontinuous layer having a surface area occupancy factor in the range of 50% to 98%, or 53% to 83%, or even 63 % and 83%.

Therefore, advantageously, the present invention makes it possible to form a multilayer of thin layers with a single functional layer that has, when deposited on a transparent substrate, a visible light transmission Tl > 50% and a light reflection in the visible R ^l (on the multilayer side) less than 20% with relatively neutral colors in transmission and in reflection, while at the same time showing an emissivity lower than that of the substrate alone.

Therefore, advantageously, the present invention allows to form a multilayer of thin layers with 1, 2, 3, 4 or even more metallic functional layers in which all the metallic functional layers based on silver or made of silver of the multilayer are discontinuous in a way that the multilayer shows a high mechanical resistance and/or a high chemical resistance.

Advantageous details and features of the invention will become apparent from the following non-limiting examples shown using the accompanying figures, which illustrate:

- in Figure 1, a multilayer with a single functional layer according to the invention, the discontinuous functional layer being deposited directly on a lower barrier coating and directly under an upper barrier coating; Y

- in figure 2, a double glazing solution that incorporates a multilayer with a single functional layer according to figure 1;

- in Figure 3, binary TEM images, from left to right, for a silver functional layer having a surface area occupancy factor of 53% to 98%;

- in figure 4, the adhesion energy Ad, in J/m2, measured for the four cases of discontinuous layer in figure 3 and compared with the theoretical value, Gm, according to the models, for these same four cases, in silver surface fraction function ("silver surface fraction" or SSF) which is the surface area occupancy factor;

- in figure 5, the transmission of light in the visible T ^l , using black triangles, and the reflection of light in the visible R ^l , using black rectangles, of a multilayer of thin layers of type Z as a function of the thickness e of the silver layer;

- in Figure 6, the theoretical emissivity, using inverted black triangles, and the measured emissivity, using black dots, of a multilayer of Z-type thin layers as a function of the thickness e of the silver layer together with that of the substrate alone, without multilayer;

- in figure 7, the light transmission in the visible T ^l , using black rhombuses, of a multilayer of thin layers of type Y as a function of the thickness e of the silver layer for a gradient that goes from 1.0 to 8 0.0 nm and using black squares for a multilayer of Y-type thin layers as a function of the thickness e of the silver layer for a gradient from 0.0 to 2.0 nm;

- in figure 8, the absorption of light in the infrared Abs, using black rhombuses, of a multilayer of thin layers of type Y as a function of the thickness e of the silver layer for a gradient from 1.0 to 8, 0 nm and using black squares for a multilayer of thin layers of the type Y as a function of the thickness e of the silver layer for a gradient from 0.0 to 2.0 nm;

- in figure 9, the reflection of light in the visible R ^l , using black rhombuses, of a multilayer of thin layers of type Y as a function of the thickness e of the silver layer for a gradient that goes from 1.0 to 8 0.0 nm and using black squares for a multilayer of Y-type thin layers as a function of the thickness e of the silver layer for a gradient from 0.0 to 2.0 nm;

- in figure 10, the absorption spectrum of a multilayer of thin layers of type Y as a function of the lambda wavelength and as a function of the thickness e of the silver layer;

- in figure 11, the resistance per square R in ohms per square of the multilayers in examples 1 to 4 as a function of the thickness of the silver layer;

- in figure 12, the Abs infrared absorption of the multilayers in examples 1 to 4 as a function of the thickness of the silver layer;

- in figure 13, the color in the transmission Ct in the Lab diagram, for the multilayers in examples 1 to 4, as a function of the thickness of the silver layer; Y

- in figure 14, the color in the Cr reflection in the Lab diagram, on the multilayer side, for the multilayers in examples 1 to 4, as a function of the thickness of the silver layer

- in figure 15, the transmission of light in the visible T ^l , as a dashed line, and the reflection of light in the visible R ^l , as a solid line, for example 6, as a function of the thickness e of the layer silver;

- in figure 16, the absorption in the infrared for example 6, as a function of the thickness e of the silver layer; - in figure 17, the emissivity, as a dashed line, and the resistance per square, as a solid line, for example 6, as a function of the thickness e of the silver layer;

- in figure 18, a multilayer with two functional layers according to the invention, each of the two discontinuous functional layers being deposited directly on an anti-reflective coating and directly under an anti-reflective coating; Y

- in figure 19, a multilayer with three functional layers according to the invention, each of the three discontinuous functional layers being deposited directly on an anti-reflective coating and directly under an anti-reflective coating.

In figures 1, 2, 18 and 19, the proportions between the thicknesses of the various layers or of the various elements are not strictly respected in order to facilitate their reading.

Figure 1 shows a structure of a multilayer 34 with a single functional layer according to the invention deposited on a transparent glass substrate 30, and more precisely on one face 31 of this substrate 30, where the single functional layer 140, based on silver or in metal alloy containing silver and preferably made only of silver, is disposed between two anti-reflective coatings, the underlying anti-reflective coating 120 located below the functional layer 140 in the direction of the substrate 30 and the superimposed anti-reflective coating 15 disposed above the functional layer 140 . functional layer 140 on the opposite side with respect to the substrate 30.

These two antireflective coatings 120, 160 each comprise at least one antireflective layer 124, 164. Optionally, on the one hand, the functional layer 140 can be deposited directly on a lower blocking coating 130 located between the underlying anti-reflection coating 120 and the functional layer 140 and, on the other hand, the functional layer 140 can be deposited directly below a blocking coating 150 located between the functional layer 140 and the superimposed anti-reflective coating 160 .

The upper and lower barrier layers, although deposited in the form of metal and present as metallic layers, are in practice oxidized layers, since their primary function is to oxidize during cell deposition to protect the functional layer.

This antireflective coating 160 can be terminated with an optional protective layer 168, in particular oxide-based, specifically substoichiometric in oxygen.

When a multilayer with a single functional layer is used in a multiglazing unit 100 with a double glazing structure, as illustrated in Figure 2, this glazing unit comprises two substrates 10, 30 that are held together by a structure 90 of double glazing. frame and which are separated from each other by a gas separation contact surface 15 .

Therefore, the glazing provides a separation between an external space ES and an internal space IS. Due to its high mechanical strength, the multilayer according to the invention can be placed on face 4 (on the innermost shell of the building when considering the incident direction of sunlight entering the building and on its face facing inwards) .

Figure 2 illustrates this positioning (showing the incident direction of sunlight entering the building by the double arrow) on face 4 of a multilayer 14 of thin layers positioned on an external face 31 of the substrate 30 in contact with the space exterior ES, the other face 29 of the substrate 30 being in contact with the gas separation interface 15.

However, it can also be envisaged, in this double glazing structure, that one of the substrates has a laminar structure; however, there is no possible confusion because, in such a structure, there is no gas separation layer.

As a first stage, the studies related to a Z-type multilayer, which has the structure: substrate/ZnO/Ag/ZnO, with each ZnO layer having a thickness of 10 nm, then with a Y-type multilayer, which has the structure: substrate/ZnO/Ag/ZnO, each layer of ZnO having a thickness of 5 nm, then five sets of examples have been implemented to test various materials to span a discontinuous layer, and finally an example of a complete multilayer.

For all the multilayers below in this document, the deposition conditions for the layers are:

Therefore, the deposited layers can be classified into three categories:

i- layers of dielectric/anti-reflective material, showing an n/k ratio over the entire visible wavelength range greater than 5: Si3N4:Al, TiOx, TiO2, ZnO, SnZnOx

iii- metallic functional layers of material with reflective properties in the infrared and/or for solar radiation: Ag

iii- lower and upper barrier layers designed to protect the functional layer against a change in its nature during the deposition of the multilayer: Ni, NiCr; its influence on the optical and energetic properties is generally ignored when its thickness is negligible (equal to or less than 2 nm).

In all the examples, the multilayer of thin layers was deposited on a substrate made of transparent soda lime glass with a thickness of 4 mm, of the Planilux brand, distributed by the company SAINT-GOBAIN. For these multilayers,

- R indicates: the resistance per square of the multilayer, in ohms per square;

- Ab indicates: the absorption in the infrared range;

- T ^l indicates: the transmission of light in the visible in %, measured according to illuminant D65 at 2°;

- R ^l indicates: the reflection of light on the glass side (surface of the substrate opposite to that on which the multilayer is deposited) in the visible in %, measured according to illuminant D65 at 2°;

- Ct indicates: the color in transmission a* and b* in the LAB system, measured according to illuminant D65 at 2°;

- Cr indicates: the color in reflection a* and b* in the LAB system measured according to illuminant D65 at 2°, on the coated side of the substrate (side 31).

According to the invention, a metallic functional layer 140 is a discontinuous layer having a surface area occupancy factor (proportion of the surface of the layer that is located just below the functional layer and that is covered by the metallic functional layer) in the range between 50% and 98%.

Figure 3 shows, from left to right:

- a surface area occupancy factor of 53% obtained with a silver thickness of 2nm,

- a surface area occupancy factor of 63% obtained with a silver thickness of 3nm,

- a surface area occupancy factor of 84% obtained with a silver thickness of 4nm,

- a surface area occupancy factor of 98% obtained with a silver thickness of 5 nm, obtained for a multilayer Z of thin layers having the structure: substrate/ZnO/Ag/ZnO, each layer of ZnO having a thickness 10nm.

Herein, when referring to the thickness e of a discontinuous functional layer, this will not be the thickness measured in the areas covered by the functional layer or an average thickness, but the thickness that would be obtained if the functional layer were continuous.

This value can be obtained by considering the rate of deposition of the layer (or more precisely the scanning rate of the substrate within the deposition chamber for the metallic functional layer), the amount of material sprayed per unit of time, together with the area of surface to which the deposition is applied. This thickness is very practical because it allows a direct comparison with continuous functional layers.

Therefore, the thickness e is the thickness that would be measured if the deposited layer were continuous.

In practice, if, under the same magnetron sputtering deposition conditions (very low pressure, target composition, substrate scanning speed, cathode electrical power) the thickness of the functional layer is typically 10 nm, it is necessary and enough to reduce the scanning speed of the substrate by half to obtain half the thickness of a functional layer, that is, 5 nm.

In this figure 3, the observations by transmission electron microscopy, TEM, are shown in binary mode (black-white). In all four sections of this figure, silver is white and ZnO is black.

It has been observed that, for a multilayer Z of this type, the adhesion energy is more or less constant for a thickness of silver greater than 5 nm: this energy is in the range between 1.0 and 1.5 J/m2 , which is a fairly low value.

Figure 4 shows the adhesion energy that has been measured, Ge (curve with black dots), for the multilayer Z, in the four previous cases of a discontinuous metallic functional layer 140: this adhesion energy is always greater than the energy of adhesion observed for a silver thickness greater than 5 nm.

Furthermore, this measured binding energy Ge is higher than the theoretical binding energy Gm (curve with open squares), as calculated by models available in the scientific literature.

Figure 5 shows, using the black triangles, the light transmission T ^l , of the Z-type multilayer, as a function of the thickness e of the silver metallic functional layer: this light transmission remains within a useful range of from 60 to 80% for a silver thickness equal to or less than 5 nm, that is, for a surface area occupancy factor in the range of 50% to 98%.

Figure 5 also shows, using the black rectangles, the light reflection R ^l , of the Z-type multilayer, as a function of the thickness e of the metallic silver functional layer: this light reflection remains within a range useful from 10 to 20% for a silver thickness equal to or less than 5 nm, that is, for a surface area occupancy factor in the range between 50% and 98%.

Figure 6 shows, by way of example, the emissivity of a substrate alone, ^eg , without coating: this is the horizontal line located at approximately 90%.

Figure 6 also shows that it is possible to measure with the Z-type multilayer an emissivity ^ez (black dots) that is lower than that of the substrate only for a silver thickness equal to or less than 5 nm, that is, for a factor of surface area occupancy in the range of 50% to 98%.

Table 1 below in this document summarizes the measured emissivities for Type Z multilayers as a function of silver layer thickness and surface area occupancy factor:

Table 1

Theoretical calculations show that, with the Z-type multilayer, it is possible to obtain an emissivity ^ez (inverted black triangles) that is lower than that of the substrate only for a silver thickness equal to or less than 5 nm, that is, for a surface area occupancy factor in the range of 50% to 98%, while higher than observed. Therefore, Figures 5 and 6 show that it is possible to form a Z-type multilayer which has a relatively low light reflection, a relatively high light transmission and a fairly high emissivity, but which can be useful for certain applications, although the adhesion energy is very high, as can be seen in figure 4. In order to try to better understand the phenomena observed in Z-type multilayers, a second multilayer, called "Y-type", which has the structure : substrate/ZnO/Ag/ZnO with each ZnO layer having a thickness of 5 nm and, for this Y-type multilayer, silver gradients were tested, on the one hand, between 1.0 and 8.0 nm and, on the other, between 0 and 2.0 nm.

Absorption has been observed to increase monotonically between 0 and 2.0 nm from 2% (bare glass absorption) to an absorption in the range of 20 to 23%. As before, subsequently the absorption decreases rapidly between 2 and 6 nm of silver until reaching values of 5-6%. It is also interesting to note that a part of the absorption level is associated with an increasing level of reflectivity for small thicknesses of Ag. This implies that it would be possible to slightly modulate the absorption level by adjusting for optical interference effects.

Furthermore, it has been observed that, between 0 and about 2 nm, the Y-type multilayer dye becomes increasingly blue with (referring to the LAB system) a very strong decrease in b*. Between about 2 and about 4 nm, the behavior changes dramatically to red with a strong increase in a* and b*. Finally, between about 4 and about 8nm, the colors revert to blue/neutral. An interpretation of this behavior can be provided by observing the variation of the absorption spectrum as a function of the thickness of the silver, in figure 10:

- at very low thicknesses of silver (1.0 and 2.5 nm), the absorption spectrum shows a peak whose position shifts towards red increasing the thickness of Ag, ranging from 675 nm for 1 nm to 695 for 2 0.5nm; This peak undoubtedly corresponds to the surface plasmons of the Ag “nanoobjects”;

- from 2.5nm to 4.0nm, the position of the absorption peak shifts towards blue from 695nm to 535nm losing intensity to a great extent; In parallel, the absorption level in the red/near IR remains high; This thickness range corresponds to a discontinuous layer of silver with a surface area occupancy factor in the range of 50% to 83%;

- finally, from 6.0 to 8.0 nm, the absorption level decreases strongly with a correspondingly higher reflection: this corresponds to the thickness interval for which the silver layer is continuous.

The resistance per square of Y-type multilayers has been measured locally. For this type of multilayer, it has been possible to measure resistances per square starting from 3.0 nm, which indicates the start of percolation of the Ag film.

Five sets of examples, numbered 1 to 5, have been implemented to test various functional layer thicknesses depending on the nature of the layer chosen to lie directly below in the direction of the substrate (referred to as the "wetting layer" 128) and various parameters have been measured for each series by way of example.

For these examples, each of the two anti-reflective coatings 120, 160 comprises an anti-reflective layer 124, 164.

Table 2 below shows the geometric or physical thicknesses (rather than optical thicknesses) in nanometers for each of the layers in examples 1 to 5, some of them being according to the invention and others being outside of it. the invention:

Table 2

The antireflective layer 124 in all examples and the wetting layer 128 in example 4 are based on silicon nitride and, more precisely, are made of Si3N4:Al (written "SiN" in figures 11 to 14); they are deposited from a silicon metal target doped with 8% aluminum by weight.

The antireflective layer 164 in all examples and the wetting layer 128 in example 3 are based on zinc oxide and, more precisely, are made of ZnO (written "AZO" in figures 11 to 14); they are deposited from a ceramic target composed of zinc oxide ZnO; however, it is possible to use, for example, a metal target and perform reactive sputtering in the presence of oxygen.

Table 3 below in this document summarizes the maximum thicknesses for the silver functional layer, some of them being outside the invention, which allowed to form a discontinuous functional layer, depending on the nature of the layer located just above:

Table 3

It has been found that fairly high light transmissions Tl (greater than 50%) and fairly low light reflections ^Rl (equal to or less than 20%) could be obtained:

Table 4

It has also been observed that:

- the resistance per square R of the multilayers can adopt reasonable values (less than 200 Q per square), as can be seen in figure 11,

- the absorption can be relatively low (less than or equal to 25%), as can be seen in figure 12,

- the transmission color Ct can be blue-green (a* negative or slightly positive), as can be seen in figure 13, and

- the color in reflection Cr can be blue-green (a* negative or slightly positive), as can be seen in figure 14.

Colors, both transmission and reflection, have not been optimized for testing, but the rules for optimization based on anti-reflective layer thicknesses appear to be the same as for multilayers with full (or continuous) metallic functional layers. .

To confirm these observations, a series of examples have been implemented, some of them being according to the invention and others being outside the invention, based on example 6 having the following geometric or physical structure and thicknesses in nanometers (in instead of optical thicknesses), with reference to figure 1 :

Table 5

This Example 6 has a typical low emission dip coatable multilayer structure, based on Example 3 comprising a ZnO wetting layer under the functional layer, and following the teachings of European Patent Application No. EP 718 250 , that is, by providing a barrier layer of silicon nitride on each side of the ZnO/Ag assembly.

The first test performed is the HH (high humidity) test. This consists of placing the samples in a climatic chamber for the desired duration (7 days, 14 days and 56 days) and removing them without turning off the chamber to observe them. For Ag thicknesses of 1, 2, 3, 4, and 5 nm, few defects appear and do not change over time. This is in contrast to 6, 7 and 8nm where corrosion starts to appear after 7 days of testing and only increases.

It has been observed that the smaller the silver thicknesses, the better the multilayer resists the EST mechanical resistance test, as is usually done. For Ag thicknesses of 1 and 2 nm, the first scratch appears at 7 N, compared to 8 nm for Ag where its appearance occurs from 0.3 N. These results agree with the increase in adhesion energy observed during the first tests.

After annealing at 650 0C for 10 min (for ESTTT tests) simulating a forming heat treatment or dip coating, the observations remain similar. For smaller thicknesses of Ag, scratches appear more quickly. For Ag thicknesses of 1 and 2 nm, the first scratch is observed at 3 N, compared to 8 nm for Ag, where its appearance is observed from 0.1 N.

To evaluate the optical "performances" of the series of examples 6, the transmission of light in the visible and the reflection of light in the visible as a function of the thickness of the silver are indicated in figure 15, the absorption of light as a function of the thickness of the silver is indicated in figure 16 and the resistance per square as a function of the thickness of the silver in figure 17.

Light absorption increases between 1 and 3 nm of silver to relatively high values (approximately 16 to 18%), then decreases after 3 nm to values close to the “usual” values of conventional low-emission multilayers with a continuous silver layer with a thickness of 6 to 8 nm. The decrease in absorption after 3 nm is concomitant with the increase in light reflection.

It has been found that, starting from 3 nm, it is possible to measure resistances per square below 100 ohms/square. The curve of resistance per square versus absorption shows a rapid increase in absorption for resistances per square in the range of 5 to 40 ohms/square. This absorption subsequently stabilizes around the maximum value of approximately 20%.

In addition, it has been observed that at lower thicknesses of Ag (from 1 to 4 nm), the color in transmission is blue. Figures 18 and 19 respectively show a structure of a multilayer 35 with two functional layers according to the invention and a structure of a multilayer 36 with three functional layers according to the invention, deposited on a transparent glass substrate 30, and more precisely on one side. 31 of this substrate 30.

Each functional layer 140, 180, 220, based on silver or a metallic alloy containing silver and preferably only silver, is disposed between two anti-reflective coatings, an underlying anti-reflective coating 120, 160, 200 located below each layer 140, 180, 220 functional layer in the direction of substrate 30 and an overlay anti-reflective coating 160, 200, 240 disposed on top of each functional layer 140, 180, 220 on the opposite side with respect to substrate 30.

Each antireflective coating 120, 160, 200, 240 comprises at least one antireflective layer 124, 164, 204, 244. To explore the application of the discovery regarding the high adhesion energy of metallic functional layers based on silver or made of silver that are discontinuous, outside the invention, three examples have been implemented, having the following structure and geometric thicknesses or physical in nanometers (instead of optical thicknesses), with reference to figures 1, 18 and 19:

Table 6

The TiO 2 titanium dioxide deposited antireflective layers 124, 164, 204 and 244 have an optical index (at 550 nm) of 2.4.

These multilayers have been deposited on a transparent glass substrate with a thickness of 4 mm.

It has been observed that these examples 7 to 9 also show an increase in adhesion energy with respect to the theoretical adhesion energy.

The following table presents the main optical characteristics of examples 7 to 9 and compares these characteristics with those of a multilayer (for example 10) for solar control by absorption, comprising a single functional layer of NbN nitride with a thickness of 1, 5 nm, sandwiched below in the direction of the glass substrate with a thickness of 4 mm by a layer based on silicon nitride with a thickness of 10 nm, and above by a layer based on silicon nitride with a thickness of 30 nm .

Table 7

Therefore, it has been observed that it is possible to form:

- a multilayer with a single metallic functional layer that is discontinuous (for example 7),

- a multilayer with two metallic functional layers with two discontinuous functional layers (for example 8), - a multilayer with three metallic functional layers with three discontinuous functional layers (for example 9), showing an average light transmission in the visible (between 50% and 70%) and that is within the same interval as that of the example 10, together with an average selectivity s (of approximately 1.1) and which is within the same range as that of example 10.

In addition, the colors obtained, both in transmission (Ct) and in reflection (Cr), are within the desired ranges: blue, blue-green.

The present invention is described in the text above by way of example. It goes without saying that those skilled in the art are able to implement other variants of the invention without, however, departing from the scope of the patent as defined in the claims.

Claims (15)

Yo. A substrate (30) coated on one side (31) with a multilayer of thin layers (34, 35, 36) comprising at least one metallic functional layer (140, 180, 220) based on silver or made of silver and two coatings antireflective coatings (120, 160, 200, 240), each of said antireflective coatings comprising at least one antireflective layer (124, 164, 204, 244), said functional layer (140) being disposed between the two coatings (120, 160) antireflective, characterized in that said, or each, metallic functional layer (140, 180, 220) is a discontinuous layer having a surface area occupancy factor in the range of between 50% and 98%, or even between 53% and 83% and because said, or each, discontinuous metallic functional layer (140, 180, 220) has a thickness e: - 1.0 < and < 4.5 nm, or even 1.0 < and < 4.0 nm, deposited on a layer based on titanium dioxide TiO2, or - 1.0 < and < 4.5 nm, or even 1.0 < and < 4.0 nm, deposited on a layer based on zinc and tin oxide SnZnOx, or - 1.0 < and < 5.0 nm, or even 1.0 < and < 4.5 nm, deposited on a layer based on zinc oxide ZnO, or - 1.0 < and < 7.0 nm, or even 1.0 < and < 6.0 nm, deposited on a layer based on silicon nitride Si3N4, or - 1.0 < and < 5.0 nm, or even 1.0 < and < 4.0 nm, deposited on a nickel-based layer. 2. The substrate (30) according to claim 1, characterized in that the antireflective coating (120) disposed between the face (31) and a first, or the only, discontinuous metallic functional layer (140) comprises an antireflective layer (124) of medium index made of a material having a refractive index in the range of between 1.8 and 2.2 at 550 nm, this medium index antireflective layer (124) preferably being oxide-based and/or having this layer (124 ) medium index antireflection preferably a physical thickness in the range between 5 and 35 nm. 3. The substrate (30) according to claim 1, characterized in that the antireflective coating (120, 160, 200) disposed below each discontinuous metallic functional layer (140, 180, 220) comprises an antireflective layer (124, 164, 204) index made of a material having a refractive index in the range of between 1.8 and 2.2 at 550 nm, said medium index antireflective layer (124, 164, 204) being preferably oxide-based and/or This mid-index antireflective layer (124, 164, 204) preferably having a physical thickness in the range of 5 to 35 nm. 4. The substrate (30) according to claim 1, characterized in that said anti-reflective coating (120) disposed between the face (31) and a first, or the only, discontinuous metallic functional layer (140) comprises an anti-reflective layer (124) of high index made of a material having a refractive index in the range of between 2.3 and 2.7 at 550 nm, this high index antireflective layer (124) being preferably oxide-based and/or having this layer (124 ) high index antireflection preferably a physical thickness in the range of between 5 and 25 nm. 5. The substrate (30) according to claim 1, characterized in that the antireflective coating (120, 160, 200) disposed below each discontinuous metallic functional layer (140, 180, 220) comprises an antireflective layer (124, 164, 204) high index made of a material having a refractive index in the range between 2.3 and 2.7 at 550 nm, said high index antireflective layer (124, 164, 204) being preferably oxide-based and/or This high index anti-reflective layer (124, 164, 204) preferably having a physical thickness in the range of 5-25 nm. The substrate (30) according to any one of claims 1 to 5, characterized in that the antireflective coating (160) disposed on top of a first, or the only, discontinuous metallic functional layer (140), on the opposite side with respect to the face (31), comprises a medium index anti-reflective layer (164) made of a material having a refractive index in the range between 1.8 and 2.2 at 550 nm, this anti-reflective layer (164) being of medium index preferably oxide-based and/or this medium index antireflective layer (164) preferably having a physical thickness in the range of between 5 and 35 nm. 7. The substrate (30) according to any one of claims 1 to 5, characterized in that the antireflective coating (160, 200, 240) arranged on top of each discontinuous metallic functional layer (140, 180, 220), on the opposite side with With respect to face (31), it comprises a medium index antireflective layer (164, 204, 244) made of a material having a refractive index in the range between 1.8 and 2.2 at 550 nm, said layer being preferably oxide-based medium index antireflective layer (164, 204, 244) and/or this medium index antireflective layer (164) preferably having a physical thickness in the range of between 5 and 35 nm. The substrate (30) according to any one of claims 1 to 5, characterized in that the antireflective coating (160) disposed on top of a first, or the only, discontinuous metallic functional layer (140), on the opposite side with respect to the face (31), comprises a high index antireflective layer (164) made of a material having a refractive index in the range between 2.3 and 2.7 at 550 nm, this antireflective layer (164) being of high index preferably oxide-based and/or this high index antireflective layer (164) preferably having a physical thickness in the range of between 5 and 25 nm. 9. The substrate (30) according to any one of claims 1 to 5, characterized in that the antireflective coating (160, 200, 240) arranged on top of each discontinuous metallic functional layer (140, 180, 220), on the opposite side with With respect to face (31), it comprises a high-index antireflective layer (164, 204, 244) made of a material having a refractive index in the range of between 2.3 and 2.7 at 550 nm, said layer being preferably oxide based high index antireflective layer (164, 204, 244) and/or this high index antireflective layer (164, 204, 244) preferably having a physical thickness in the range between 5 and 25 nm. 10. The substrate (30) according to any one of claims 1 to 9, characterized in that said multilayer (35) comprises two metallic functional layers (140, 180) based on silver or made of silver and three coatings (120, 160, 200 ) antireflective, each metallic functional layer being disposed between two antireflective coatings. 11. The substrate (30) according to any one of claims 1 to 9, characterized in that said multilayer (36) comprises three metallic functional layers (140, 140, 220) based on silver or made of silver and four coatings (120, 120 , 160, 200, 240) antireflective, each metallic functional layer being disposed between two antireflective coatings. The substrate (30) according to any one of claims 1 to 11, characterized in that said functional layer (140) is deposited directly on a lower barrier coating (130) disposed between this functional layer (140, 180, 220) and the antireflective coating (120) underlying this functional layer and/or at least one of said functional layers (140, 180, 220) is deposited directly below a barrier top coating (150) disposed between this layer (140, 180, 220) and the reflective coating (160) superimposed on this functional layer and in that the lower barrier coating (130) and/or the upper barrier coating (150) comprises a thin nickel or titanium based layer having a thickness physical e' such that 0.2 nm <e'< 2.5 nm. 13. The substrate (30) according to any one of claims 1 to 12, characterized in that the last layer (168) of the multilayer (34, 35, 36), which is the furthest from the substrate (30), is based on an oxide, preferably substoichiometrically deposited, and in particular based on titanium dioxide or based on a mixture of zinc oxide and titanium. 14. A multiple glazing (100) comprising at least two substrates (10, 30) held together by a framework structure (90), said glazing forming a separation between an external space (ES) and an internal space (IS ), wherein at least one gas separation layer (15) is arranged between the two substrates, a substrate (30) being according to any one of claims 1 to 13. 15. A method for depositing at least one metallic functional layer (140, 180, 220) based on silver or made of silver, and two anti-reflective coatings (120, 160) in order to form a substrate (30) coated with a multilayer of thin layers (34, 35, 36) according to any one of claims 1 to 13, said or each metallic functional layer (140, 180, 220) being a discontinuous layer having a surface area occupancy factor in the range between 50% and 98%, or even between 53% and 83%.